Suppression of cross-hatched polariton disorder in GaAs/AlAs microcavities by strain compensation

Zinc-blende semiconductor heterostructures grown in the [001] direction with a small lattice mismatch accommodate stress by developing a cross-hatch dislocation pattern. In GaAs based planar microcavitiesgrown by molecular beam epitaxy, this pattern creates a potential landscape for exciton-polaritons, causing scattering and localization. We report here on suppressing the cross-hatch by introducing strain-compensating AlP layers into the center of the low index AlAs layers of the distributed Bragg reflectors. We observe a reduction of the cross-hatch dislocation density by at least one order of magnitude for 1.1 nm thick AlP layers, which correspond to an effective AlAs0.985P0.015 low index layer. These compensated structures show a remaining polariton disorder potential in the 10 μeV range.